DISTRIBUTION OF THE EUPHAUSIACEA IN THE BENGUELA CURRENT 345 



Stylocheiron elongatum G. O. Sars 

 Stylocheiron elongatum G. O. Sars, 1883, p. 32. 

 Eleven larvae were encountered between 1000 m. and 500 m. at station WS 976. One was taken 

 in the upper 50 m. at station WS 997. 



Stylocheiron longicorne G. O. Sars 

 Stylocheiron longicorne G. O. Sars, 1883, p. 32; S. mastigophorum (partim) Chun, 1887, p 30. 

 One larva was taken between 500 m. and 250 m. at station WS 997. 



Stylocheiron afhne Hansen 



Stylocheiron affine Hansen, 1910, p. 118. 



Five larvae were taken in the upper 250 m. at station WS 976. 



A small number of unidentifiable larvae occurred at stations WS 976, 977, 978, 988, 997, 998, 999 

 and eggs were present in the upper layers at stations WS 976, 977, 978, 986, 996, 997, 998 and 999. 



REMARKS 



Physical oceanographic conditions in the Benguela Current (Currie, 1953) are somewhat similar to 

 those found in the California Current, and a very close similarity in phytoplankton populations and 

 successions in the two currents has been stressed by Hart (1953). 



In general, the distribution of comparable species of euphausiids substantiates this similarity in 

 the two regions. Nyctiphanes capensis occupies the same inshore niche in South African waters that 

 N. simplex does in Californian waters. Euphausia lucens, reaching the northern limit of its range in the 

 Benguela, may be compared with E. pacifica, which reaches its southern limit in the California 

 Current. The distribution of Nyctiphanes megalops in this survey is very similar to that of N. difficilis 

 in California, and that of Euphausia recurva and Thysanoessa gregaria is the same in both regions. 



Curiously enough, species with comparable distributions in the two currents show remarkable 

 morphological similarities. The appearance of Nyctiphanes capensis closely resembles that of N. sim- 

 plex. This is true of all four species of Nyctiphanes. These species all occur in areas of upwelling where 

 conditions are roughly the same. 



Euphausia lucens and E. pacifica are undoubtedly the most closely morphologically allied species 

 in this large genus. Even the copulatory organs of the males show many points of similarity. 



Nematoscelis difficilis and N. megalops are so closely similar that the females are inseparable. On 

 these grounds Einarsson (1942) cancelled N. difficilis. The males are separable on small but consistent 

 differences in the copulatory organs, however, and the species has, therefore, been revived (Boden, 



1954)- 

 The distribution of euphausiids in the Pacific is now fairly well understood (Brinton, unpublished) 



and it may become possible to draw further analogies when the results of the second survey of the 



Benguela Current have been evaluated. 



